Improvement in truss-bridges



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MILO S.- OAR'ITER AND HOSEA B. CARTIER, OF ST. LOUIS, MISSOURI.

Letters Patent No. 104,110, dated June 14, 1370..

IMPRO'V'EMENT IN TRUSS-BRIDGES.

The Schedule referred to in these Letters Patent and making part of the same.

To all whomit may concern:

Beit known that we, Mino S. CARTTER and HosnA B. GARTTER, of St. Louis, in the county of St. Louis and in the State of' Missouri, have invented certain new and useful Improvements in Truss-Bridges; and do hereby declare that the following is a full, clear, and exact description thereof,reference being had to the accompanying drawing making a part of this specitication, in whichy Figure 1 is a side elevation of a Howe truss-bridge, constructed with our improvements;

Figure 2 is' a plan view of a portion of the floor ot' the same;

Figure 3 is a plan view of the lower side of a portion of one of the bottom chords, showing one section joint;

.Figure 4 is a bottom plan of a section joint, enlarged;

Figure 5 is a plan of one of the friction seats;

Figure (i is a cross-section of the saine on the line a: a: ot' g. 5;

Figure 7 is a transverse section of a lowe'r chord, on the line y y ofig. 3, showing, also, part of a floor- `timber with -its truss-rod;

Figure 8 is a transverse section of a lower chord, at an angle block, on the line z z of iig. 3;

Figure 9 is a side elevation of a lower chord, showing the end of an angle-block; and

Figure 10 is a perspective view of the upper side of a shoe, with the top plate removed.

Letters of like name and kind refer to like parts in each of the figures.

This invention is an improvement in the Howe truss-bridge; and l It consists in the manner of constructing the sections of the lower chord and in connecting the same to each other and to the bridge, so that there will bed no shearing strain upon the joint-bolts, and so that said joints will be accessible for repairs or for the application of protective coats of' paint.

Heretofore,'in constructing truss-bridges with iron chords at the bottom, the different sectionsA of said chords have been secured to each other by bolts only, hy which means said bolts were subjected toa shearing strain, more or less powerful, according to the weight of the superstructure. The constant action of such strain has always caused the lower chords to give way irst at the joints, which failure has been enhanced by the inacessibility of said joints for the purpose of applying to the same protective coatings of paint.

To ohviate these objections, in our invention the chord-sections are connected together by means of in- 4 terlocking projections, which receive all tensile strain and are bound together by means of bolts passing through the same. hIn the annexed drawingl A represents the upper chord, constructed in ythe 'usual manner; t

Bthe end posts;

C the main braces;

I) the counter-braces; and

E the tension-rods, which parts, being common to all i Howe truss-bridges, need no further description.

The vlower chords, F, are constructed in sections, which; for convenience, should be equal in length to the distance between the feetof the braces C, and, in

sections.

forming a section, has, formed upon one side, at its end, a head, having agthickness about equal to the thickvertical, angular shoulder, which rakes inward, so as to interlock with the head y' of the adjoining bar G of the next section.

Passing transversely through the bars G and G', near their ends, are two bolts, H, the object of which is to prevent displacement of the parts of the joint, the tensile strain upon the chord being received and sustained by the heads g and g.

At each end of the chord F is a section, composed of bars Gr, provided, at their inner ends/,with the before-described interlocking head g, while their outer ends are constructed with a T- shaped head, h, by means of which aconnectiou is made with the shoe N.

As seen in iigs.' 3 and 10, the shoe N is constructed .with a plain lower surface, while its upper side is cov- `ered by means of a plate, I, provided with a horizontal step for the reception of the lower ends ofthe posts B, with an angular step, J, for the lower ends ofthe first for the reception ofthe post tension-rods E'.

The interior of the shoe is provided with a recess chord over' the heads h, and in depth to the thickness of said heads, while a number ot' channels, i, correspending in size, shape, and position with the chordhars G, and extending longitudinally outward from said recess, receive said bars and permit their heads, h, to engage with the ends of said recess, as shown in figs. 3 and 10. By means of the plate I the chord and shoe are secured hrmly together.

Ihe joints between the intermediate chord-section (composed of the hook-headed bars G', joined as shown in tig. 4,) are covered by means of angle-blocks K, provided at their ends with flanges k, which pass downward upon either side of the chord.

Between each pair of interlocking bars G' is placed a packing-block, L, for the purpose of giving the necessary width to the chord, and also to afford space be- `tween said bars for the center tension-rod, which passes addition thereto, one-half the length `of the lap of the.V

As seen in figs. 3 and 4,cachof the flat bars G,'

ness of said bar, and terminating at its inner end in a pair ot' braces, C,A and with suitable vertical. openings' lcorresponding in width to the breath of the end of the gether with the clamp, are placed diagonally to the downward through the center ot' the angle-block and joint, while the outer rods pass through the ends of said anglc-blocksoutside of the chord, and,by means of a clamp or plate, M, placed over their lower ends and extending transversely across said chord, secures said angle-block and chord firmly together.

The shoe N rests in a friction seat, O, which rests' upon and is secured to the wall-plates P, upon the top of the pier or abutment Q, said friction seat being provided with flanges o, which project upward upon either side of the shoe and hold it rmly in position, laterally, while allowing such longitudinal movement of the shoe as may be required by the expansion or contraction of the materials of the lower chord under thermal variations.

In order to afford greater bearing-surface upon the j wall-plates, four lugs o r flanges, q, corresponding in width to said wall-plates, project-from and form a part v of the friction-seat, as show n in figs. 2 and`5.

The floor-timbers It rest in chairs, S, placed at regular intervals upon the chord F, and are secured thereto by means of two bolts s, which, passing downward through said timbers, the chairs, the chord, and a plate or'elamp, T, are provided, at their'- lower ends, with screw-threads and nuts in the usual manner.

In order to allow the bolts s to pass through the floor-timbers uponI either side of the center, they, to-

line of the bridge, as shown.

v If required, each door-timber may be trussed, as shown in g. 7, in which event it will be'necessary to groove or score the lower side of each timber from its ends inward, so as to admit the'truss-rod U, or to form each timber of two pieces, with a packing of plank placed between to cover said rod, but, in either case, the washer placedbetween the truss-rod nut and the end of the timber laps over the solid portions, so as to give a firm bearing to the rod.

The usual diagonal brace-rods W may be employed to connect the lower chords, as shown.v

In actual construction, we thoroughly coat the surfaces of the parts at the joints with paint, and interpose between the angle-blocks, chairs, 85e., and between the chord-bars, sheets of lead, so that the surfaces thus covered are fully protected, while Ythe remaining portions of the chord, being readily accessible, may be covered with paint at any time.

Having thus fully set forth the nature and merits of our invention,`

lVhat we claim as new, and desire to secure by Letters Patent, is

' Thedower or tension-chord F, composed of the bars G and G', provided with the solid hooked heads g, and connected togetheitby means of the interlocking of said heads,-the bolts H, and` the, packing-blocks L, substantially as shown and described.

Also, the angle-block K, constructed inthe manner shown and described, and combined with the plate or clamp M' and the interlocked chord-bars, as to receive and cover the joint, substantially as set forth.

Also, the friction-seat O, constructed with. the laterally-projecting bearings q, adapted to the wall-plates I?, in combination with the s hoe N, substantially as and for the purpose shown.

Also, the metallic tension-chord F, constructed ot' sections joined together by means of solid interlocking heads and'transversely-hinding ho{ts`,in combination with thc shoe N, the end posts B, the main and counter-braces C and `D, respectively, the tension-rods E, and the upper chords A, substantially as shown and described, the whole iorn'ling an improvement upon the Howe truss-bridge.

In testimony that we claim the foregoing, we have hereunto set our hands this 28th day of March, 1870.

' .MILO S. CARTTER.

HOSEA B. GARTTER.

Witnesses:

JAMES H. COMFORT, .0. T. FORD. 

